1. Field of the Invention
The present invention relates to a compressor and a method of using the compressor, and more particularly, to a compressor with a compact and inexpensive structure which does not require drilling a body thereof and a method of using the compressor.
2. Description of the Related Art
A compressor for air-conditioning of a vehicle, which is provided with a rotation detecting mechanism to detect a rotational failure resulting from seizure or the like, has been conventionally known. The rotation detecting mechanism is constructed, for example, by forming a through-hole 102 through a housing member 101 made of a nonmagnetic material and fitting a detection sensor 104 in the through-hole 102 via an O-ring 103 as shown in FIG. 5. The detection sensor 104 converts a change in a magnetic flux flowing from a magnet 106 to an iron core 107 in accordance with rotation of the detection body 105 into a voltage by means of a pickup coil 108, thereby detecting a rotational state of the detection body 105.
In the above described conventional rotation detecting mechanism, however, the housing member 101 needs to be drilled so as to form the through-hole 102, which leads to an increase in the production cost of the compressor. Further, a sealing structure employing the O-ring 103 is required, which leads to a further increase in the production cost of the compressor. In addition, there is a problem, for example, that foreign matters that have adhered to the detection sensor 104 may enter the compressor and cause seizure of the compressor.
In view of this background, a conventional compressor is known, which solves the above described problem (e.g., see Patent Documents 1 and 2). In this conventional compressor, a detection sensor is provided outside a housing member, and there is no need to drill the housing member.
In the compressor disclosed in the above-mentioned Patent Document 1, a detector 18 is provided outside a body of the compressor, and a magnetic flux leaking out from an electromagnetic clutch 6 is sequentially conducted through a drive shaft 7, a rotational base 8 (a detection body) moving in association with the drive shaft 7, and a bolt 14 (a fastener) for connecting the body, so that a circulative magnetic circuit is formed. A change in the magnetic flux is caused between the rotational base 8 and the bolt 14 via a periodic motion of the rotational base 8, and the detector 18 detects the change in the magnetic flux. A rotational speed of the compressor is detected based on this change, that is, a detection result obtained from the detector 18. Thus, this compressor is advantageous in that high detecting performance can be achieved with a simple construction.
In the compressor disclosed in the above-mentioned Patent Document 2, a magnetic sensor 150 having a magnetic impedance element (an MI element) whose impedance changes according to an external magnetic field is provided outside a body 1 of the compressor, and a permanent magnet 7 serving as a magnetic flux generating source is embedded in an outer peripheral portion of a swash plate 6 serving as a detection body. In addition, the permanent magnet 7 and the magnetic sensor 150 are so arranged as to face each other sometime while the swash plate 6 rotates by 360°. With this construction, since the magnetic element of the magnetic sensor 150 is a high-sensitivity MI element, subtle fluctuations in the magnetic field resulting from rotation of the swash plate 6 can be detected even from the outside of the body 1. Consequently, this compressor is advantageous, for example, in that detection of a rotational speed is made possible with high sensitivity and high accuracy.
According to the above-mentioned Patent Document 1, however, a magnetic sensor is arranged at a head portion of the fastener or on a stator side of the electromagnetic clutch 6 facing the fastener. This causes a problem that the axial total length of the compressor is increased because of a space for mounting the sensor.
According to the above-mentioned Patent Document 2, the magnetic flux generating source (the permanent magnet 7) is provided in the detection body inside the compressor. Therefore, this magnetic flux generating source may fall from the detection body and cause seizure or the like of the compressor. Besides, there is a problem, for example, that the necessity of the magnetic flux generating source entails an increase in the production cost of the compressor.
Patent Document 1: Japanese Patent Application Publication No. Hei 6-299960
Patent Document 2: Japanese Patent Application Publication No. 2002-195854